Obesity is a major public health problem. At least 15 million American adults are obese, and the number is rising. Childhood obesity is also increasing in prevalence and currently affects approximately 11-22 percent of children aged 6 to 11. Childhood obesity is associated with serious negative physical, emotional, and social consequences. Obese children are at high risk for becoming obese as adults; 24-44 percent of obese adults were obese as children. The risk of an obese child becoming an obese adult is especially high when at least one parent is obese. To date, adult obesity is known to be resistant to treatment. In contrast, promising long-term effects have been found with children who received behavioral family-based weight loss treatment. However, even with state-of-the-science programs, a substantial percentage of children (i.e., over 40 percent) regain all or most of the weight lost once treatment ends. The proposed study will be the first to examine the efficacy of two strategies designed to improve the long-term maintenance of weight loss in children. Over a 5-year period, 216 obese 9- to 11-year old children who have at least one obese parent will participate, along with the overweight parent, in a 20-week behavioral family-based weight loss treatment. Children will then be stratified by percent overweight change and post-weight-loss level of social problems, and randomly assigned to one of two 4-month maintenance interventions or to a no-continued treatment control. The behavioral skills-based maintenance intervention confronts the declining motivation to engage in weight-maintenance behaviors, incorporates specific skills for weight maintenance, and teaches coping skills and relapse prevention techniques. The social facilitation maintenance treatment uses socially-based approach to enhance peer support, increase parental instrumental support, improve body image, and teach effective responses to teasing as methods of sustaining weight maintenance behaviors (i.e., healthy diet and physical activity). Because the social facilitation maintenance intervention targets the social environment, the investigators posit that it may promote the most natural source of long-term encouragement for energy balance behaviors. The proposed study will examine whether the content of the maintenance sessions or extended treatment is important in improving long-term maintenance. Follow-up assessments will occur at the end of the maintenance phase of treatment, as well as at 12 and 24 months following the initial weight loss treatment. Effective maintenance treatments in children will have a substantial impact on children's immediate and future physical, psychological, and social well being. Improving long-term effects for pediatric obesity is one of the most promising directions in preventing adult obesity.